Sampling

• simple random sampling - each member of the population has an equal chance of being selected for the sample.
• systematic - using a sampling frame, a random starting point is chosen and then every nth term on the list.
• stratified - ensures subgroups are adequately represented in the whole sample population.
• Quota - sample is based on specific criteria
• convenience / opportunity sampleing - e.g. first five fish caught in a pond.
• self selecting sample - people volunteering to be part of the sample.
• categorical / quantitive data - in categories (e.g. rounded to the nearest...)
• numerical / qualitive - exact, numerical values
• standard deviation - how close values are to the mean. i.e. the spread.
• interpercentile range:

  • the difference between two percentiles.